New warning about Loopback 4.x get in the way of the output

[HugoPoi]

Description/Steps to reproduce

1. npm install loopback-cli
2. npx lb export-api-def --json
3. Warning is printed in stdout, not stderr

LoopBack 3 is in Maintenance LTS mode, only critical bugs and critical
security fixes will be provided. The support ends in December 2020. We
urge all LoopBack 3 users to migrate their applications to LoopBack 4
as soon as possible. Refer to our Migration Guide for more information
on how to upgrade: https://loopback.io/doc/en/lb4/migration-overview.html

...JSON_DATA...

Expected result

The warning should be in stderr

[dhmlau]

@bajtos, what do you think?

[bajtos]

Thank you @HugoPoi for reporting the issue. I agree with you that the current behavior is not great and like your proposal to print the warning to stderr. Would you like to contribute the change yourself? See Contributing code get started.